1. Field of the Invention
This invention concerns a display equipment, which performs display at sub-pixel precision based on an original image, which is not a vector image but a raster image (pixel precision: in the case of a font, means not a vector font but a raster font), and art related to this display equipment.
2. Description of the Related Art
Display equipment that employs various types of display devices is in common use. Such display devices include color LCD""s, color plasma displays, and other display devices, in which three light-emitting elements, which respectively emit light of the three primary colors of R, G, and B, are aligned in a fixed order to form one pixel. A plurality of the pixels thus formed are aligned in a first direction to form one line. A plurality of lines are aligned in a second direction, which is orthogonal to the first direction, to form a display screen of the display device.
There are also many display devices having relatively narrow display screens which make detailed display difficult to achieve. Such narrow display screens may be found in portable telephones, mobile devices, computers, etc. When an attempt is made to display a small character, photograph, or complex picture, etc. on a small display device, part of the image tends to become smeared and unclear.
To solve the above problem, attempts have been made to display in sub-pixel units. A sub-pixel unit is defined as one of the three light-emitting units. Improved picture quality may be achieved by separately driving the three light-emitting elements for R, G, and B of the pixel.
Literature (titled: xe2x80x9cSub-pixel Font Rendering Technologyxe2x80x9d) concerning sub-pixel display, discloses on the Internet a system which uses one pixel formed by the three light-emitting elements for R, G, and B to improve the clarity of the display on a narrow screen. The present inventors have checked this literature upon downloading it from the site, http://grc.com, or its subordinate.
This art is described with reference to FIGS. 24 to 28. In the following description, the image of the alphabetic character, xe2x80x9cAxe2x80x9d, is used as an example of the image to be displayed.
FIG. 24 is a schematic view of a single line in which single pixels are formed from three light-emitting elements as described above. The horizontal direction in FIG. 24 (the direction in which the light-emitting elements of the three primary colors of R, G, and B are aligned) is defined as the first direction. The orthogonal, vertical direction is defined as the second direction. The definition of directions is arbitrary, and is for purposes of description, without the intention to limit the present invention. The order of alignment of the light-emitting elements besides R, G, and B is possible, and this prior art and this invention can be applied in the same way described even if the order of alignment is changed.
A plurality of pixels (sets of three light-emitting elements) are aligned in a single row in the first direction to form a single line. A plurality of lines are aligned in the second direction to form the display screen.
With this sub-pixel technology, the original image is, for example, an image such as shown in FIG. 25. In this example, the character, xe2x80x9cAxe2x80x9d, is displayed over an area having seven pixels in the horizontal direction and seven pixels in the vertical directions. Where each of the R, G, and B light-emitting elements is handled as a single pixel to perform sub-pixel display, a font, which has a definition of three times that of the above-described image in the horizontal direction, is prepared, as shown in FIG. 26, over an area consisting of 21 (=7xc3x973) pixels in the horizontal direction and 7 pixels in the vertical direction.
Then as shown in FIG. 27, a color is determined for each of the pixels in FIG. 25 (i.e., not the pixels of FIG. 26 but the pixels of FIG. 25). However, since color irregularities will occur if display is performed as it is, a filtering process, using factors such as shown in FIG. 28(a), is applied. Factors concerning the luminance are shown in FIG. 28, and the luminance values of the respective pixels are adjusted by multiplying a factor, for example, of 3/9 in the case of the central target pixel, 2/9 in the case of an adjacent pixel, and 1/9 in the case of the pixel next to the adjacent pixel.
When such a filtering process is applied to pixels of the colors shown in FIG. 27, blue is adjusted to light blue, yellow is adjusted to light yellow, red is adjusted to light red, and cyan is adjusted to light cyan as shown in FIG. 28(b).
An image to which such a filtering process has been applied is then allocated to the respective light-emitting elements of FIG. 26 to perform sub-pixel display.
(First Problem)
With this prior art, an image (FIG. 26), which is magnified by three in definition in the first direction with respect to the original image (FIG. 26), must be retained separately and yet statically.
Generally, with fonts or other sets of numerous images, simply increasing the types of fonts requires increasing the system resource. In particular, an art that requires large system resources is difficult to employ in a portable telephone, mobile computer, etc. where there are several limitations in terms of system resource.
Furthermore, since the art is premised on the ability to statically use the three-time magnified image itself, a display, with which the definition has been magnified by three, cannot be performed, for example, for a facial portrait image or other arbitrary image that has been downloaded from a server.
The prior art has the above-described first problem that, although sub-pixel precision display is not impossible, the burden placed on the system resources is large and the range in which sub-pixel display can be performed is limited.
(Second Problem)
Also, with the prior art, there is a difficulty in terms of adjustment of the character intervals. This point is described by way of the example shown in FIG. 16. The drawing illustrates schematically a sub-pixel display by the prior art. In this example, the character string, xe2x80x9cThisxe2x80x9d, is displayed.
The respective characters (that is, the xe2x80x9cTxe2x80x9d, xe2x80x9chxe2x80x9d, xe2x80x9cixe2x80x9d, and xe2x80x9csxe2x80x9d) are formed of sub-pixels as shown at the left side of FIG. 16 or as previously prepared font arranged in sub-pixels. Four sub-pixel images are thus obtained for the four characters, xe2x80x9cTxe2x80x9d, xe2x80x9chxe2x80x9d, xe2x80x9cixe2x80x9d, and xe2x80x9csxe2x80x9d, respectively.
With the prior art, the images of the respective characters are aligned and displayed as shown at the right side of FIG. 16.
However with the prior art, the positions of these four images are set in pixel units and cannot be adjusted more finely. Also, although the four images of xe2x80x9cTxe2x80x9d, xe2x80x9chxe2x80x9d, xe2x80x9cixe2x80x9d, and xe2x80x9csxe2x80x9d are sub-pixel images, the spaces between these images are not sub-pixel images. There is thus the second problem that when viewed as a whole, a character string, such as xe2x80x9cThisxe2x80x9d, is not fixed in pitch and was thus non-uniform.
Also, in the case of a format such as equal spacing (similar to typewriter spacing), which is shown in FIG. 17(a), since the character intervals can only be adjusted at pixel precision, the character intervals tend to be non-uniform.
(Third Problem)
The prior-art display method enables only a binary black-white display (or a gray-scale display of low gradation) and cannot accommodate the case where at least one of the foreground or background is in color.
A first object of the present invention is to resolve the above-described first problem by providing a display equipment and related art that enables sub-pixel display with a light system resource load even when a three-times magnified image is not known in advance.
A second object of this invention is to resolve the above-described second problem by providing a display equipment, with which character strings can be formatted in a finer manner and which enables displays that excels in uniformity as a whole.
A third object of this invention is to resolve the above-described third problem by providing a display method at sub-pixel precision that enables color display.
(1) In order to achieve the first object, a display equipment of a first mode of this invention is equipped with a display device, in which three light-emitting elements, which respectively emit light of the three primary colors of R, G, and B, are aligned in a fixed order to form one pixel, the pixels are aligned in a first direction to form one line, and a plurality of such lines are aligned in a second direction, which is orthogonal to the first direction, to form the display screen, a display image storage means, which stores display image information to be displayed on the display device, and a display control means, which controls the display device to perform display based on the display image information stored by the display image storage means.
The display device has an original image data storage means, which stores a raster image to be displayed currently, and a three-times magnified pattern determination means, which, based on the raster image in the original image data storage means, determines a three-times magnified pattern with which the definition is magnified by three in the first direction, and the display image information, based on the three-times magnified pattern determined by the three-times magnified pattern determination means, is stored in the display image storage means.
The three-times magnified pattern determination means determines a three-times magnified pattern, with which a target pixel, in the raster image stored in the original image data storage means, is magnified by three in the first direction, in accordance with a rectangular reference pattern of a total of (2n+1)xc3x97(2 m+1) (where n and m are natural numbers) pixels consisting of the target pixel and the pixels that surround the target pixel, and the display control means controls the display device to perform display upon allocating the three-times magnified pattern to the three light-emitting elements that comprise one pixel.
With this arrangement, since the three-times magnified pattern determination means dynamically determines the three-times magnified pattern based on the raster image stored in the original image data storage means, the three-times magnified pattern does not have to be retained statically. Thus in comparison to the case where the three-times magnified pattern is stored statically, the burden placed on the system is lightened to enable application to portable telephones, mobile computers, and other equipment with severe limitations in system resource.
The raster image and the three-times magnified pattern for the raster image need not be known in advance. Thus for a wide range of images, such as a facial portrait image that has been downloaded from a server, a sub-pixel image, which is improved in definition in a practical way, is displayed in a manner that is easy to view.
With a display equipment of a second mode of this invention, n=1 and m=1.
With this arrangement, the reference pattern is a rectangular, 3xc3x973 pixel set, the reference pattern can take any of 512 forms, and sub-pixel display is realized using a simple process.
With a display equipment of a third mode of this invention, the raster image stored in the original image data storage means is a bit map font, a bit map image, formed by raster development of a vector font, or a raster image that is not a font.
By this arrangement, sub-pixel display is performed for images of various forms.
With a display equipment of a fourth mode of this invention, the three-times magnified pattern determination means references a reference pattern storage means which stores according to three-times magnified pattern determination rules, to determine the three-times magnified pattern.
With this arrangement, since the three-times magnified pattern is determined upon referencing the reference pattern storage means, the three-times magnified pattern is determined at high speed and the display response is improved.
With a display equipment of a fifth mode of this invention, information for pattern matching of the reference pattern is stored in the reference pattern storage means.
By this arrangement, the three-times magnified pattern is determined by pattern matching.
With a display equipment of a sixth mode of this invention, a bit string, which expresses the reference pattern in the form of bits, and information indicating a three-times magnified pattern for this bit string, are stored in an associated manner in the reference pattern storage means.
With this arrangement, a three-times magnified pattern is searched rapidly and readily using the bit string.
With a display equipment of a seventh mode of this invention, the three-times magnified pattern determination means determines the three-times magnified pattern by referencing the calculation results of a three-times magnified pattern logical operation means, which performs logical operations based on the reference pattern.
By this arrangement, since the three-times magnified pattern is determined only by logical operations even if the reference pattern is not stored, savings in storage area is achieved.
(2) In order to achieve the second object, a display equipment of an eighth mode of this invention is equipped with a display image storage means, which stores a display image, a display means, with which three light-emitting elements, which respectively emit light of the three primary colors of R, G, and B, are aligned in a fixed order to comprise one pixel and which performs display based on the display image stored in the display image storage means, a character string storage means, which stores a character string to be displayed, a format information storage means, which stores format information on the respective characters of the character string to be displayed, a character string image generating means, which generates, based on the format information, a character string image in which the character string stored by the character string storage means is formatted in an integral manner, a sub-pixel image generating means, which generates a sub-pixel image, with which the generated character string image is mapped at the level of the light-emitting elements, and stores the sub-pixel image in the display image storage means, and a control means, which allocates the sub-pixel image in the display image storage means to the respective light-emitting elements and makes the display means perform display.
By this arrangement, a character format, which is based on one-pixel units in the prior art, is displayed more finely at sub-pixel precision. Here, though a display result is generally poorer in definition than a printed result, this difference in definition is reduced by the sub-pixel display to improve the WYSIWYG (What you see is what you get) feature.
In particular, since sub-pixel mapping is performed at the level of the character string image itself, in which a character string is formatted integrally, sub-pixel mapping is performed not only on the characters that comprise the character string but also on the intervals between characters. The precision of character intervals is thus improved and the pitch is made constant for the character string as a whole to enable a display of high uniformity.
A display equipment of a ninth mode of this invention is equipped with a filtering process means, which transfers to the sub-pixel image generating means, information on the energy collection of the character string image, generated by the character string image generating means, among the respective light-emitting elements that comprise a single pixel and/or light-emitting elements adjacent to the above-mentioned light-emitting elements.
By this arrangement, suitable factors for performing filtering are selected to perform appropriate energy collection from among the respective light-emitting elements and to thereby realize a display that is easy to view.
With a display equipment of a tenth mode of this invention, the character string is a word, row, column, or paragraph.
With this arrangement, various character forms are handled at sub-pixel precision.
With a display equipment of an eleventh mode of this invention, the format information concerns kerning, both-end equal spacing, right justify, left justify, or centering.
By this arrangement, various formats are handled at sub-pixel precision.
(3) In order to achieve the third object, a twelfth mode of this invention provides a display method, by which a display device, in which three light-emitting elements, which respectively emit light of the three primary colors of R, G, and B, are aligned in a fixed order to form one pixel, such pixels are aligned in a first direction to form one line, and a plurality of such lines are aligned in a second direction, which is orthogonal to the first direction, to form the display screen, is made to perform display. The display method includes a step of acquiring three-times magnified image data, consisting of sub-pixels resulting from the magnification of a raster image to be currently displayed by three in the first direction, a step of subjecting the three-times magnified image data to a filtering process, a step of determining, on the basis of the filtering process results, a mixing ratio of the foreground color and the background color of each pixel, a step of acquiring the foreground colors and the background colors of the respective pixels, a step of determining a mixed color, in which the foreground color and background color are mixed at the sub-pixel level, for each pixel in accordance with the determined mixing ratio, and a step of controlling the display device to perform color sub-pixel display in accordance with the mixed color.
By this arrangement, sub-pixel display is performed not only for a black and white display but also where either or both the foreground and background are in color. Thus even in the case of color display, the display is made easy to view, the smearing of characters is limited, and the clarity of the display is improved by sub-pixel display.
With a display method of a thirteenth mode of this invention, the mixing ratio is determined by normalizing the values resulting from filtering.
By this arrangement, the filtering results are incorporated accurately in the mixed color.
With a display method of a fourteenth method of this invention, the foreground color value, background color value, and mixing ratio are expressed in 8 bits.
By this arrangement, computer operations are facilitated and the ease of use by one skilled in the art is improved.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.